CN117160482A

CN117160482A - Alkyne selective hydrogenation catalyst

Info

Publication number: CN117160482A
Application number: CN202210603639.3A
Authority: CN
Inventors: 苟尕莲; 车春霞; 李永兵; 谭都平; 何崇慧; 梁玉龙; 温翯; 韩伟; 张峰; 边虎
Original assignee: Petrochina Co Ltd
Current assignee: Petrochina Co Ltd
Priority date: 2022-05-27
Filing date: 2022-05-27
Publication date: 2023-12-05

Abstract

The invention relates to an alkyne selective hydrogenation catalyst, in particular to a catalyst for selective hydrogenation of acetylene in the preparation of olefin from methanol, wherein the carrier is alumina or mainly alumina, and has a bimodal pore distribution structure, and the specific surface area of the catalyst is 1-15 m ² Preferably 1 to 10m ² And/g. Wherein the aperture of the small hole is 45-80 nm, and the aperture of the large hole is 300-950 nm. The catalyst at least contains Fe,Zn, pd, ni, cu where Fe and Zn are supported in solution, pd is supported in both microemulsion and solution, and Ni and Cu are supported in microemulsion. The method comprises the steps of taking the mass of a catalyst as 100%, wherein the content of Fe is 0.5-1.0%, the content of Pd is 0.005-0.015%, the content of Pd carried by the microemulsion is 1/15-1/10 of the content of Pd carried by a solution method, the weight ratio of Zn to Fe is 0.8-2.5, the content of Ni is 0.4-7.5%, the weight ratio of Cu to Ni is 0.15-0.90, the reduction temperature of the catalyst adopted by the alkyne removal method is lower, the yield of green oil in the alkyne removal process is low, the catalytic performance and the anti-coking performance are excellent, and the preparation cost is low.

Description

Alkyne selective hydrogenation catalyst

Technical Field

The invention relates to a high-efficiency alkyne selective hydrogenation catalyst, in particular to a high coking resistance catalyst for selectively hydrogenating acetylene in a product of preparing ethylene from methanol.

Background

The low-carbon olefin such as ethylene, propylene and the like is an important basic chemical raw material, and along with the development of economy, the demand of the modern chemical industry for the low-carbon olefin is gradually increased, and the contradiction between the supply and the demand is also increasingly outstanding. So far, the important way to prepare low-carbon olefins such as ethylene, propylene and the like is still to prepare the low-carbon olefins by catalytic cracking of naphtha and light diesel (all from petroleum), and the important way to prepare the raw material resources such as naphtha, light diesel and the like as raw materials for producing ethylene is faced with the increasingly serious shortage situation. Therefore, the development of non-petroleum resources for producing lower olefins is becoming increasingly important.

The MTO process for preparing ethylene and propylene from methanol and the MTP process for preparing propylene from methanol are important chemical technology at present. The technology takes methanol synthesized by coal or natural gas as a raw material to produce low-carbon olefin, and is a core technology for developing non-petroleum resources to produce products such as ethylene, propylene and the like.

The process for preparing olefin from methanol is a key step in the industrial chain of preparing olefin from coal, and mainly comprises the steps of taking methanol as a raw material under proper operation conditions, selecting a proper catalyst, and preparing low-carbon olefin by dehydration of methanol in a fixed bed reactor and a fluidized bed reactor. According to different target products, the process for preparing olefin from methanol is divided into the process for preparing ethylene from methanol, the process for preparing propylene from methanol. The whole reaction of preparing olefin from methanol can be divided into two stages: dehydration stage, cracking reaction stage

1. Dehydration stage

2CH ₃ OH→CH ₃ OCH ₃ +H ₂ O+Q

2. Cleavage reaction stage

The reaction process mainly comprises the catalytic cracking reaction of dimethyl ether which is a dehydration reaction product and a small amount of unconverted raw material methanol, and comprises the following steps:

main reaction (olefin formation):

nCH ₃ OH→C _n H _2n +nH ₂ O+Q

nCH ₃ OH→2C _n H _2n +nH ₂ O+Q

n=2 and 3 (primary), 4, 5 and 6 (secondary)

The above olefin products are all in the gaseous state.

Side reactions (alkane, aromatic hydrocarbon, carbon oxides and coking):

(n+1)CH ₃ OH→C _n H _2n+2 +C+(n+1)H ₂ O+Q

(2n+1)CH ₃ OH→2C _n H _2n+2 +CO+2nH ₂ O+Q

(3n+1)CH ₃ OH→3C _n H _2n+2 +CO ₂ +(3n-1)H ₂ O+Q

n＝1，2，3，4，5…………

nCH ₃ OCH ₃ →C _n H _2n-6 +3H ₂ +nH ₂ O+Q

n＝6，7，8…………

after dehydration, cracking and separation of methanol, the ethylene material at the top of the deethanizer still contains 5-100 ppm of acetylene, which affects the polymerization process of ethylene and causes the degradation of product quality, and the ethylene material needs to be removed by a selective hydrogenation method. The selective hydrogenation of trace acetylene in ethylene materials has extremely important influence on the polymerization process of ethylene, ensures that the hydrogenation has enough activity, has good acetylene removal performance under the condition of low acetylene content, ensures that the acetylene content at the outlet of the reactor reaches the standard, and also ensures that the hydrogen content at the outlet of the reactor reaches the standard, and besides the selectivity of the catalyst is excellent, the ethylene can generate ethane as little as possible, and the hydrogenation process is ensured not to bring loss of ethylene of the device.

Alkyne and diene selective hydrogenation catalysts are obtained by supporting noble metals such as palladium on a porous inorganic support (US 4762956). In order to increase the selectivity of the catalyst and reduce the deactivation of the catalyst caused by green oil produced by oligomerization during hydrogenation, the prior art has employed a method of adding, for example, a group IB element to the catalyst as a co-catalytic component: pd-Au (US 4490481), pd-Ag (US 4404124), pd-Cu (US 3912789), or alkali metal or alkaline earth metal (US 5488024) is added, and alumina, silica (US 5856262), honeycomb-like bluestone (CN 1176291) or the like is used as a carrier. The patent US4404124 prepares a selective hydrogenation catalyst with active component palladium shell distribution by a step-by-step impregnation method, and can be applied to selective hydrogenation of carbon two and carbon three fractions so as to eliminate acetylene in ethylene and propyne and propadiene in propylene. US5587348 uses alumina as a carrier, adjusts the action of promoter silver and palladium, and adds alkali metal and chemically bonded fluorine to prepare the carbon hydrogenation catalyst with excellent performance. The catalyst has the characteristics of reducing green oil generation, improving ethylene selectivity and reducing the generation amount of oxygen-containing compounds. US5519566 discloses a method for preparing a silver and palladium catalyst by wet reduction, wherein an organic or inorganic reducing agent is added into an impregnating solution to prepare a silver and palladium two-component selective hydrogenation catalyst.

The traditional carbon two hydrogenation catalysts are prepared by adopting an impregnation method, and the active phases of the catalyst are Pd and Ag bimetallic. This method has the following disadvantages: (1) The dispersion of the active component can not be accurately controlled and the randomness is strong under the influence of the pore structure of the carrier. (2) Under the influence of the surface tension and solvation effect of the impregnating solution, the precursor of the metal active component is deposited on the surface of the carrier in an aggregate form, and uniform distribution cannot be formed. (3) The selectivity requirement of the carbon two hydrogenation on the catalyst is higher, and the traditional preparation method promotes the exertion of the auxiliary agent effect by increasing the amount of Ag, so that the transmission of hydrogen is blocked, the possibility of oligomerization is increased, the green oil generation amount is increased, and the service life of the catalyst is influenced. The occurrence of the three phenomena easily causes poor dispersibility of the metal active components, low reaction selectivity and high green oil yield, thereby affecting the overall performance of the catalyst. In addition, noble metals Pd and Ag are used as active components, so that the preparation cost of the catalyst is high.

CN201110086174.0 forms a polymer coating layer on the surface of a carrier by adsorbing a specific polymer compound on the carrier, and reacts with the polymer by using a compound with a functional group, so that the compound has a functional group capable of complexing with an active component, and the active component is subjected to a complexing reaction on the functional group on the surface of the carrier, thereby ensuring the ordered and high dispersion of the active component. By adopting the patent method, the carrier adsorbs a specific high molecular compound, and the hydroxyl groups of the alumina are subjected to chemical adsorption, so that the amount of the carrier adsorbed the high molecular compound is limited by the hydroxyl groups of the alumina; the complexation of the functionalized polymer and Pd is not strong, the loading amount of the active component sometimes does not meet the requirement, and part of the active component is remained in the impregnating solution, so that the cost of the catalyst is increased.

In order to improve the anti-coking performance of the catalyst and reduce the surface coking degree of the catalyst, a carbon two-selective hydrogenation catalyst adopting a bimodal pore carrier and a microemulsion preparation method to load active components and a preparation method thereof are disclosed in recent years. Patent ZL201310114079.6 discloses a preparation method of a hydrogenation catalyst, wherein a catalyst carrier is mainly alumina and has a bimodal pore distribution structure. The catalyst contains Pd and Ni double active components, and the active component Pd is mainly distributed on the surface of a carrier, particularly in small holes, by making the anti-coking component Ni enter the carrier macropores in the form of microemulsion when preparing the catalyst. Patent ZL201310114371.8 discloses a carbon two-fraction selective hydrogenation method suitable for a pre-depropanization pre-hydrogenation process. The selective hydrogenation catalyst adopted by the method is alumina or alumina mainly, has a bimodal pore distribution structure, contains double active components Pd and Ni, and has an anti-coking component Ni mainly distributed in macropores. The method improves the coking resistance of the catalyst, but the reduction temperature of the single-component Ni in the macropores of the catalyst carrier reaches more than 500 ℃, and the single-component Ni is reduced at the reduction temperature, so that the active component Pd of the catalyst is aggregated, and the activity of the catalyst is greatly reduced. To compensate for the loss of catalyst activity, the amount of active component is increased, which results in a decrease in catalyst selectivity and a decrease in active component utilization.

The active components of the catalyst disclosed in CN106927993A at least contain Fe and Cu, and Cu is considered to be added into the active composition containing iron, so that the activation temperature is reduced, the formation and dispersion of an activated phase of the catalyst are facilitated, and the selectivity of the catalyst is improved. Meanwhile, the addition of Cu is beneficial to the adsorption and activation of alkyne and the improvement of the activity of the catalyst. The roasting temperature is preferably 300-400 ℃; the reduction is carried out at 260-330 ℃. Although the above method has a relatively low reduction temperature, it causes partial agglomeration of metal active components including Pd, fe, zn, etc., and affects catalytic activity.

Pd-Ag acetylene selective hydrogenation catalyst disclosed in CN105732266A, and carrier is Al ₂ O ₃ Or Al ₂ O ₃ The mixture with other oxides has Pd content of 0.025-0.060% and Ag content of 0.05-0.4% based on the mass of the catalyst of 100%. CN105732271A discloses a Pd-Cu acetylene selective hydrogenation catalyst, wherein the carrier is Al ₂ O ₃ Or Al ₂ O ₃ The mixture with other oxides has Pd content of 0.015-0.050% and Cu content of 0.02-0.3% based on the mass of the catalyst of 100%. CN107970927A discloses a Pd-series pyrolysis gas selective hydrogenation catalyst, and the carrier is Al ₂ O ₃ The main active component is Pd, the content is 0.05 to 0.12 weight percent of the total mass of the carrier, and the auxiliary active component is Ga-Ga ₂ O ₃ The content is 0.02-0.80 wt% of the total weight of the carrier. The selective hydrogenation catalysts disclosed above are catalysts which take Pd as a main active component, and have high Pd content and high preparation cost.

Disclosure of Invention

The invention relates to a high-efficiency alkyne selective hydrogenation catalyst, in particular to a high-coking-resistance catalyst for selectively hydrogenating acetylene in a product of preparing ethylene from methanol.

In the present invention, the carrier is required to have a bimodal pore distribution structure, the present invention is not particularly limited to the distribution range of macropores and pinholes of the bimodal pore distribution, and can be selected according to the reaction characteristics, such as raw materials, process conditions, active components of the catalyst, etc., and the carrier is particularly recommended to be alumina or mainly alumina, and has a bimodal pore distribution structure, wherein the pore diameter of the micropores is 45-80 nm, and the pore diameter of the macropores is 300-950 nm. The specific surface area of the catalyst is 1-15 m ² Preferably 1 to 10m ² /g。

In the invention, the active component of the catalyst at least contains Fe, zn, pd, ni, cu, wherein Fe and Zn are loaded in a solution mode, pd is loaded in a microemulsion mode and a solution mode, and Ni and Cu are loaded in a microemulsion mode. Based on the mass of the catalyst being 100%, the content of Fe is 0.5-1.0%, preferably 0.7-0.9%, the content of Pd is 0.005-0.015%, preferably 0.007-0.010%, wherein the content of Pd loaded on the microemulsion is 1/15-1/10 of the content of Pd loaded on the solution method, the weight ratio of Zn to Fe is 0.8-2.5, preferably 1.0-1.5, the content of Ni is 0.4-7.5%, preferably 3.0-6.8%, the weight ratio of Cu to Ni is 0.15-0.90, preferably 0.2-0.7; wherein Ni, cu and Pd loaded in the microemulsion mode are mainly distributed in macropores of 300-950 nm of the carrier.

The catalyst at least contains Fe, zn, pd, ni, cu, the selective hydrogenation reaction of alkyne occurs in a reaction center composed of Fe, zn and Pd, wherein Fe is a main active component of the catalyst and acts to adsorb and activate acetylene so as to catalyze the selective hydrogenation of acetylene; the bimetallic nano particles formed by Zn and Fe can further improve the hydrogenation activity of Fe due to the electronic synergistic effect of the alloy; the small amount of Pd loaded on the solution is an auxiliary active component of the catalyst, which is favorable for the rapid dissociation of hydrogen, thereby improving the catalytic performance. Because the catalyst is different from the traditional Pd-based industrial hydrogenation catalyst, the non-noble metal Fe is adopted as the main active component, the noble metal Pd is used as the auxiliary active component, the content of the noble metal Pd is low, the dosage of the noble metal Pd is greatly reduced, and the preparation cost of the catalyst is reduced.

In the catalyst, the selective hydrogenation reaction of acetylene mainly occurs in a reaction center composed of Fe, zn and Pd; ni and Cu are immersed in macropores of a carrier in the form of microemulsion, and green oil generated in the reaction is subjected to saturated hydrogenation on an active center composed of Cu and Ni.

The Cu has the function of forming Ni/Cu alloy in the roasting process, effectively reducing the reduction temperature of nickel in the reduction process, reducing the polymerization of Fe, zn and Pd at high temperature, improving the dispersity of main active components, and simultaneously modulating the saturated hydrogenation reaction performance of Ni in macropores.

For hydrogenation reaction, the hydrogenation catalyst is generally reduced before the catalyst is applied, so that the active components exist in a metal state, and the catalyst has hydrogenation activity. Because the catalyst preparation process is an elevated temperature calcination process in which the metal salt decomposes to metal oxides which form clusters, which are typically nano-sized. Different oxides, due to their different chemical properties, need to be reduced at different temperatures. However, for nano-sized metals, about 200 ℃ is an important critical temperature beyond which metal particles can aggregate quite significantly. Therefore, reducing the reduction temperature of the active component is of great importance for hydrogenation catalysts.

The invention solves the problems of catalyst coking by the following steps:

alkyne selective hydrogenation reaction occurs in main active centers of components, such as Fe, zn and Pd, and macromolecules such as green oil produced in the reaction easily enter into macropores of the catalyst. In the macroporous catalyst, ni/Cu component is loaded, wherein Ni has saturated hydrogenation function, and green oil component can generate saturated hydrogenation reaction in active center of Ni/Cu component. Because the double bond is saturated by hydrogenation, the green oil component can not undergo polymerization reaction or greatly reduce the polymerization reaction rate, the chain growth reaction is terminated or delayed, a huge molecular weight condensed ring compound can not be formed, and the condensed ring compound is easily carried out of the reactor by materials, so that the coking degree of the surface of the catalyst can be greatly reduced, and the service life of the catalyst can be greatly prolonged.

The method for controlling the Ni/Cu alloy to be positioned in the macropores of the catalyst is that Ni/Cu is loaded in the form of microemulsion, and the particle size of the microemulsion is larger than the pore diameter of the micropores of the carrier and smaller than the maximum pore diameter of the macropores. Nickel and copper metal salts are contained in microemulsions and, due to steric drag, are difficult to access into the pores of smaller size supports and thus mainly into the macropores of the support.

In the invention, cu and Ni are loaded together, so that the reduction temperature of Ni can be reduced, and the reduction temperature is generally required to reach 450-500 ℃ for completely reducing NiO, and agglomeration of Fe, zn and Pd can be caused at the reduction temperature, so that after Cu/Ni alloy is formed, the reduction temperature can be reduced by more than 100 ℃ to reach 350 ℃ compared with the reduction temperature of pure Ni, thereby relieving the agglomeration of Fe, zn and Pd in the reduction process.

In the invention, a small amount of Pd loaded on the microemulsion is on the surface of the Ni/Cu alloy, so that the reduction temperature of Ni can be further reduced to below 200 ℃ and at least 150 ℃.

In the invention, in the process of loading palladium by a solution method, the solution containing palladium enters the pores more quickly due to the siphoning effect of the pores, the palladium exists in the form of chloropalladate ions, and the palladium is targeted quickly due to the fact that the ions can form chemical bonds with hydroxyl groups on the surface of the carrier, so that the faster the solution enters the pore channels, the faster the loading speed is. So that it is more easily supported in the pores during impregnation of Pd in a solution method.

In the invention, pd is loaded by adopting two modes of a solution method and a microemulsion method, namely, most Pd is loaded by adopting a solution, and the Pd solution is recommended to adopt a supersaturation impregnation method; and (3) loading a small part of Pd in a microemulsion mode, wherein the particle size of the microemulsion is controlled to be larger than 80nm and smaller than 950nm when the microemulsion is loaded, so that the part of Pd is distributed in macropores of the carrier, and the step of loading the Pd in the microemulsion is performed after the step of loading the Ni and the Cu in the microemulsion.

In the invention, the carrier is required to have a bimodal pore distribution structure, the pore diameter of the macropores is 300-950 nm, and the pore diameter of the micropores is 45-80 nm. The carrier being alumina or mainly alumina, al ₂ O ₃ The crystal form is preferably alpha, theta or a mixed crystal form thereof. The alumina content in the catalyst carrier is preferably 80% or more, and other metal oxides such as magnesia, titania and the like may be contained in the carrier.

In the invention, the loading of Fe and Zn can be carried out by a solution supersaturation impregnation method, and the sequence of the steps of loading Fe and Zn by a solution method and Pd by a solution method is not limited.

The present invention is not particularly limited to the process of loading Ni, cu and Pd in the form of microemulsion, and Ni, cu and Pd can be distributed in the macropores of the carrier as long as the microemulsion can form a particle size of more than 80nm and less than 950nm.

In the invention, the weight ratio of the water phase to the oil phase is 4.8-6.8, the weight ratio of the surfactant to the oil phase is 0.08-0.30, and the weight ratio of the surfactant to the cosurfactant is 1.0-1.2.

The invention also provides a more specific catalyst, and the preparation method of the catalyst comprises the following steps:

(1) Dissolving precursor salts of Ni and Cu in water, adding an oil phase, a surfactant and a cosurfactant, and fully stirring to form microemulsion, wherein the particle size of the microemulsion is controlled to be more than 80nm and less than 950nm; adding the carrier into the prepared microemulsion, soaking for 0.5-4 hours, filtering residual liquid, drying for 1-6 hours at 80-120 ℃, and roasting for 2-8 hours at 300-600 ℃. Obtaining a semi-finished catalyst A;

(2) Dissolving Pd precursor salt in water, regulating the pH value to be 1.5-2.5, adding the semi-finished catalyst A into Pd salt solution, soaking and adsorbing for 0.5-4 h, drying for 1-4 h at 80-120 ℃, and roasting for 2-6 h at 400-550 ℃ to obtain a semi-finished catalyst B;

(3) The loading of Fe and Zn is carried out by a supersaturation impregnation method, namely, the prepared mixed solution of ferric salt and zinc salt is 80-110% of the saturated water absorption rate of the carrier, the pH value is adjusted to be 1-5, and the semi-finished catalyst B is roasted between 500-550 ℃ after being loaded with Fe and Zn for 4-6 hours to obtain the semi-finished catalyst C;

(4) Dissolving Pd precursor salt in water, adding an oil phase, a surfactant and a cosurfactant, and fully stirring to form microemulsion, wherein the particle size of the microemulsion is controlled to be more than 80nm and less than 950nm; adding the semi-finished catalyst C into the prepared microemulsion, soaking for 0.5-4 hours, and filtering out residual liquid; drying at 80-120 deg.c for 1-6 hr and roasting at 300-600 deg.c for 2-8 hr to obtain the catalyst.

In the above preparation steps, the step (1) and the step (2) may be interchanged, and the step (4) follows the step (1).

The carrier in the step (1) can be spherical, cylindrical, clover-shaped, tooth-shaped, clover-shaped and the like.

The precursor salts of Ni, cu, fe, zn and Pd described in the above steps are soluble salts, and may be nitrate salts, chloride salts or other soluble salts thereof.

The reduction temperature of the catalyst of the present invention is preferably 150 to 200 ℃.

The catalyst has the following characteristics:

the catalyst is different from the traditional Pd-based industrial hydrogenation catalyst, adopts non-noble metal Fe as a main active component, and noble metal Pd as an auxiliary active component, and has lower content, so that the preparation cost of the catalyst can be greatly reduced. In addition, in the aspect of reducing the coking amount of the catalyst, the hydrogenation activity of the main active component is high and is mainly distributed in the small holes, so that the selective hydrogenation reaction of acetylene mainly occurs in the small holes. With the extension of the catalyst running time, a part of byproducts with larger molecular weight are generated on the surface of the catalyst, and the substances enter the macropores more due to larger molecular size, and the stay time is longer, so that double bond hydrogenation reaction can occur under the action of the nickel catalyst, saturated hydrocarbon or aromatic hydrocarbon without isolated double bonds is generated, and substances with larger molecular weight are not generated.

The catalyst prepared by the method has the advantages that the initial activity and the selectivity of the catalyst are obviously improved compared with those of the traditional catalyst.

The catalyst of the invention has the advantages that even if the raw materials contain more heavy fractions, the green oil production amount of the catalyst is greatly increased, and the activity and selectivity of the catalyst still have no tendency to be reduced.

Detailed Description

The analytical test method comprises the following steps:

specific surface area: GB/T-5816;

pore volume: GB/T-5816;

the catalyst contains active components: atomic absorption;

microemulsion particle size distribution of Ni/Cu alloy: a dynamic light scattering particle size analyzer, on an M286572 dynamic light scattering analyzer;

the conversion and selectivity in the examples were calculated according to the following formulas:

acetylene conversion (%) =100× delta acetylene/inlet acetylene content

Ethylene selectivity (%) =100×Δethylene/Δacetylene

Example 1

And (3) a carrier: the commercial bimodal pore distribution spherical alumina carrier with the diameter of 4mm is adopted, and the mixture is roasted for 4 hours at high temperature, and 100g of the mixture is weighed. The calcination temperature and the physical properties of the carrier are shown in Table 1.

And (3) preparing a catalyst:

(1) Weighing a certain amount of nickel nitrate and copper chloride, dissolving the nickel nitrate and copper chloride in deionized water, adding a certain amount of cyclohexane, triton X-100 and n-butanol, fully stirring to form microemulsion, dipping 100g of the weighed carrier into the prepared microemulsion for 1 hour, washing the carrier to be neutral by deionized water, drying the carrier at 120 ℃ for 2 hours, and roasting the carrier at 550 ℃ for 5 hours. To obtain a semi-finished catalyst A.

(2) Weighing a certain amount of palladium nitrate, dissolving in deionized water, adjusting the pH to 1.5, soaking the semi-finished catalyst A in the prepared Pd salt solution, adsorbing for 1h, drying at 110 ℃ for 2h, and roasting at 480 ℃ for 6h to obtain the semi-finished catalyst B.

(3) Weighing ferric nitrate and zinc nitrate, preparing into a mixed solution by deionized water, adding the semi-finished catalyst B into the solution, shaking, drying at 110 ℃ for 3 hours after the solution is completely absorbed, and roasting at 500 ℃ for 4 hours to obtain the semi-finished catalyst C.

(4) A certain amount of palladium nitrate is weighed and dissolved in water, a certain amount of cyclohexane, tritonX-100 and 6.03g of n-hexanol are added and fully stirred to form microemulsion. And (3) adding the semi-finished catalyst A into the prepared microemulsion, soaking for 4 hours, washing with deionized water to neutrality, drying at 90 ℃ for 4 hours, and roasting at 600 ℃ for 2 hours to obtain the finished catalyst.

The particle size of the microemulsion prepared in the catalyst preparation process and the content of each component in the catalyst are shown in table 2.

Before use, the mixture is placed in a fixed bed reaction device, and the molar ratio is N ₂ :H ₂ Mixed gas of 1:1, at 170 ℃, reduction treatment for 12h.

The reduction temperature peak of the catalyst carrying only Ni/Cu and the catalyst carrying only Pb-Ni/Cu as in example 1 were measured, the reduction peak of the catalyst carrying only Ni/Cu was about 350℃and the reduction temperature of the catalyst carrying only Pb-Ni/Cu was about 150 ℃.

Example 2

And (3) a carrier: a commercially available bimodal pore distribution spherical carrier with a diameter of 4mm was used, which consisted of 90wt% alumina and 10wt% titania. After 4 hours of high temperature roasting, 100g of the carrier is weighed, and physical properties of the carrier are shown in Table 1.

And (3) preparing a catalyst:

(1) Weighing nickel nitrate with certain mass, dissolving copper chloride in deionized water, adding certain cyclohexane, tritonX-100 and n-hexanol, and fully stirring to form microemulsion. The carrier is added into the prepared microemulsion to be immersed for 1 hour, then washed to be neutral by deionized water, dried for 2 hours at 120 ℃, and baked for 5 hours at 550 ℃. To obtain a semi-finished catalyst A.

(2) A certain amount of palladium nitrate is weighed and dissolved in water, a certain amount of cyclohexane, tritonX-100 and 6.03g of n-hexanol are added and fully stirred to form microemulsion. And (3) adding the semi-finished catalyst A into the prepared microemulsion, soaking for 4 hours, washing with deionized water to neutrality, drying at 90 ℃ for 4 hours, and roasting at 600 ℃ for 2 hours to obtain the semi-finished catalyst B.

(3) And (3) weighing a certain amount of palladium nitrate, dissolving in water, adjusting the pH to be 2, adding the semi-finished product B into a Pd salt solution, soaking and adsorbing for 1h, drying at 110 ℃ for 2h, and roasting at 480 ℃ for 6h to obtain the semi-finished product catalyst C.

(4) Weighing a certain amount of ferric chloride and zinc chloride, dissolving in deionized water, immersing the semi-finished catalyst C in the prepared solution, drying at 110 ℃ for 3 hours, and roasting at 500 ℃ for 4 hours to obtain the finished catalyst.

Example 3

And (3) a carrier: a commercially available bimodal pore distribution spherical alumina carrier was used, 4mm in diameter. After 4 hours of high temperature calcination, 100g of the carrier is weighed, and physical indexes are shown in Table 1.

And (3) preparing a catalyst:

(1) And (3) weighing a certain amount of palladium nitrate, dissolving in water, adjusting the pH to be 2, adding the carrier into a Pd salt solution, soaking and adsorbing for 1h, drying at 110 ℃ for 2h, and roasting at 480 ℃ for 6h to obtain the semi-finished catalyst A.

(2) Weighing a certain amount of ferric chloride and zinc chloride, dissolving in deionized water, immersing the semi-finished catalyst A in the prepared solution, drying at 110 ℃ for 3 hours, and roasting at 500 ℃ for 4 hours to obtain the semi-finished catalyst B.

(3) A certain amount of nickel nitrate and copper chloride are weighed and dissolved in water, a certain amount of cyclohexane and TritonX-100 and 6.03g of n-hexanol are added and fully stirred to form microemulsion. The semi-finished catalyst B is added into the prepared microemulsion to be immersed for 4 hours, then washed to be neutral by deionized water, dried for 4 hours at 90 ℃, and baked for 2 hours at 600 ℃. Semi-finished catalyst C is obtained.

(4) A certain amount of palladium nitrate is weighed and dissolved in water, a certain amount of cyclohexane, tritonX-100 and 6.03g of n-hexanol are added and fully stirred to form microemulsion. The semi-finished catalyst C is added into the prepared microemulsion to be immersed for 4 hours, then washed to be neutral by deionized water, dried for 4 hours at 90 ℃, and baked for 2 hours at 600 ℃. Obtaining the finished catalyst.

Before use, the mixture is placed in a fixed bed reaction device, and the molar ratio is N ₂ :H ₂ Mixed gas of 1:1, at 160 ℃, reduction treatment for 12h.

Example 4

And (3) preparing a catalyst:

(1) A certain amount of nickel nitrate and copper chloride are weighed and dissolved in water, a certain amount of cyclohexane and TritonX-100 and 6.03g of n-hexanol are added and fully stirred to form microemulsion. The carrier is added into the prepared microemulsion to be immersed for 4 hours, then washed to be neutral by deionized water, dried for 4 hours at 90 ℃, and baked for 2 hours at 600 ℃. To obtain a semi-finished catalyst A.

(2) And (3) weighing a certain amount of palladium nitrate, dissolving in water, adjusting the pH to be 2, adding the semi-finished catalyst A into a Pd salt solution, soaking and adsorbing for 1h, drying at 110 ℃ for 2h, and roasting at 480 ℃ for 6h to obtain the semi-finished catalyst B.

(3) Weighing a certain amount of ferric nitrate and zinc nitrate, dissolving in deionized water, immersing the semi-finished catalyst B in the prepared solution, drying at 110 ℃ for 3 hours, and roasting at 500 ℃ for 4 hours to obtain the semi-finished catalyst C.

Example 5

And (3) preparing a catalyst:

(2) A certain amount of palladium nitrate is weighed and dissolved in water, a certain amount of cyclohexane, tritonX-100 and 6.03g of n-hexanol are added and fully stirred to form microemulsion. The semi-finished catalyst A is added into the prepared microemulsion to be immersed for 4 hours, then washed to be neutral by deionized water, dried for 4 hours at 90 ℃, and baked for 2 hours at 600 ℃. Semi-finished catalyst B was obtained.

(3) And (3) weighing a certain amount of palladium nitrate, dissolving in water, adjusting the pH to be 2, adding the semi-finished catalyst B into a Pd salt solution, soaking and adsorbing for 1h, drying at 110 ℃ for 2h, and roasting at 480 ℃ for 6h to obtain the semi-finished catalyst C.

(4) Weighing a certain amount of ferric nitrate and zinc nitrate, dissolving in deionized water, immersing the semi-finished catalyst C in the prepared solution, drying at 110 ℃ for 3 hours, and roasting at 500 ℃ for 4 hours to obtain the finished catalyst.

Before use, the mixture is placed in a fixed bed reaction device, and the molar ratio is N ₂ :H ₂ Mixed gas of =1:1 at 220 DEG CTemperature, and reduction treatment for 12h.

Comparative example 1

And (3) preparing a catalyst:

(1) A certain amount of nickel nitrate is weighed and dissolved in 70ml of deionized water, a certain amount of cyclohexane, triton X-100 and n-butanol are added, the mixture is fully stirred to form microemulsion, the carrier is immersed into the prepared microemulsion for 1 hour, and then washed to be neutral by the deionized water, dried for 2 hours at 120 ℃, and baked for 5 hours at 550 ℃. To obtain a semi-finished catalyst A.

(3) Weighing ferric nitrate and zinc nitrate, preparing into a mixed solution by deionized water, adding the semi-finished catalyst B into the solution, shaking, drying at 110 ℃ for 3 hours after the solution is completely absorbed, and roasting at 500 ℃ for 4 hours to obtain the required catalyst.

Before use, the mixture is placed in a fixed bed reaction device, and the molar ratio is N ₂ :H ₂ The catalyst was not reduced at 490 c (this comparative example uses a reduction temperature of 170 c in example 1, the catalyst performance was very low, and the reduction temperature was increased to 490 c to reduce the catalyst) for 12h.

Comparative example 2

And (3) a carrier: a commercially available bimodal pore distribution spherical carrier with a diameter of 4mm was used, which consisted of 90wt% alumina and 10wt% titania. After 4 hours of high temperature calcination, 100g of the carrier is weighed, and physical indexes are shown in Table 1.

And (3) preparing a catalyst:

(3) A certain amount of palladium nitrate is weighed and dissolved in water, the pH value is adjusted to be 2, the semi-finished catalyst B is added into a Pd salt solution, after soaking and adsorption for 1h, the semi-finished catalyst B is dried for 2h at 110 ℃, and the semi-finished catalyst C is roasted for 6h at 480 ℃.

(4) Weighing zinc chloride, preparing into solution by deionized water, immersing the semi-finished catalyst C into the prepared solution, shaking, drying at 110 ℃ for 3 hours after the solution is completely absorbed, and roasting at 500 ℃ for 4 hours to obtain the required catalyst.

Comparative example 3

And (3) preparing a catalyst:

(2) Weighing a certain amount of ferric chloride and zinc chloride, dissolving in deionized water, immersing the semi-finished catalyst A in the prepared solution, drying at 100 ℃ for 3 hours, and roasting at 500 ℃ for 4 hours to obtain the required catalyst.

The content of each component in the catalyst is shown in Table 2.

Before use, the mixture is placed in a fixed bed reaction device, and the molar ratio is N ₂ :H ₂ Mixed gas of=1:1, at 350 ℃, reduction treatment for 12h.

Comparative example 4

And (3) preparing a catalyst:

(3) And (3) weighing a certain amount of ferric chloride, dissolving in deionized water, adding the semi-finished catalyst A into the prepared solution, drying at 110 ℃ for 3 hours, and roasting at 500 ℃ for 4 hours to obtain the semi-finished catalyst B.

Before use, the mixture is placed in a fixed bed reaction device with the molar ratio ofN ₂ :H ₂ Mixed gas of 1:1, at 170 ℃, reduction treatment for 12h.

Comparative example 5

The catalyst using Pd as the main active component and Ag as the auxiliary active component is prepared in the comparative example, and the catalytic performance of the catalyst of the invention is compared.

And (3) preparing a catalyst:

(2) Weighing a certain amount of silver nitrate, dissolving in deionized water, immersing the semi-finished catalyst A in the prepared solution, drying at 110 ℃ for 3 hours, and roasting at 500 ℃ for 4 hours to obtain the finished catalyst.

The catalyst preparation process and the content of each component in the catalyst are shown in table 2.

Before use, the mixture is placed in a fixed bed reaction device, and the molar ratio is N ₂ :H ₂ Mixed gas of 1:1, at 150 ℃, reduction treatment for 12h.

Comparative example 6

The comparative example Fe was added to the macropores in the form of a microemulsion:

(2) And weighing a certain amount of zinc chloride, dissolving in deionized water, immersing the semi-finished catalyst A in the prepared solution, drying at 110 ℃ for 3 hours, and roasting at 500 ℃ for 4 hours to obtain the semi-finished catalyst B.

(3) A certain amount of ferric chloride is weighed and dissolved in water, a certain amount of cyclohexane, tritonX-100 and n-hexanol are added, and the mixture is fully stirred to form the microemulsion. The semi-finished catalyst B is added into the prepared microemulsion to be immersed for 4 hours, then washed to be neutral by deionized water, dried for 4 hours at 90 ℃, and baked for 2 hours at 600 ℃. Semi-finished catalyst C is obtained.

(4) Weighing a certain amount of nickel nitrate, dissolving copper chloride in water, adding a certain amount of cyclohexane and TritonX-100, and fully stirring n-hexanol to form microemulsion. The semi-finished catalyst C is added into the prepared microemulsion to be immersed for 4 hours, then washed to be neutral by deionized water, dried for 4 hours at 90 ℃, and baked for 2 hours at 600 ℃. Semi-finished catalyst D was obtained.

(5) A certain amount of palladium nitrate is weighed and dissolved in water, a certain amount of cyclohexane, tritonX-100 and n-hexanol are added, and the mixture is fully stirred to form microemulsion. The semi-finished catalyst D was added to the prepared microemulsion and immersed for 4 hours, then washed to neutrality with deionized water, dried for 4 hours at 90℃and calcined for 2 hours at 600 ℃. Obtaining the finished catalyst.

Table 1 physical properties of catalyst carriers of examples and comparative examples

Table 2 catalyst active ingredient content for examples and comparative examples

The above catalyst was evaluated for performance in a fixed bed reactor.

TABLE 3 reaction mass composition

Table 4 results of evaluation of Pd and Fe, zn, ni, cu catalysts

Of course, the present invention is capable of other various embodiments and its several details are capable of modification and variation in light of the present invention by one skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. A catalyst for selective hydrogenation of alkyne is prepared from alumina or alumina as carrier and has dual-peak pore distribution structure and specific surface area of 1-15 m ² Preferably 1 to 10m ² And/g, wherein the pore diameter of the small pore is 45-80 nm, and the pore diameter of the large pore is 300-950 nm; the catalyst at least contains Fe, zn, pd, ni, cu, wherein Fe and Zn are loaded in a solution mode, pd is loaded in a microemulsion mode and a solution mode, and Ni and Cu are loaded in a microemulsion mode; based on the mass of the catalyst being 100%, the content of Fe is 0.5-1.0%, preferably 0.7-0.9%, the content of Pd is 0.005-0.015%, preferably 0.007-0.010%, the weight ratio of Zn to Fe is 0.8-2.5, preferably 1.0-1.5%, the content of Ni is 0.4-7.5%, preferably 3.0-6.8%, the weight ratio of Cu to Ni is 0.15-0.90, preferably 0.2-0.7; wherein Ni, cu and Pd loaded in the microemulsion mode are mainly distributed in macropores of 300-950 nm of the carrier.

2. The alkyne selective hydrogenation catalyst of claim 1, wherein the Pd content carried by the microemulsion is 1/15-1/10 of the Pd content carried by the solution method.

3. The alkyne selective hydrogenation catalyst according to claim 1, wherein the solution loading of Pd, fe, zn is by supersaturation impregnation.

4. The alkyne selective hydrogenation catalyst of claim 1 wherein during catalyst preparation, a small portion of Pd is supported as a microemulsion, the microemulsion particle size is controlled to be greater than 80nm and less than 950nm, such that the portion of Pd is distributed in the macropores of the support.

5. The alkyne selective hydrogenation catalyst of claim 1, wherein the microemulsion mode loading process comprises: dissolving precursor salt in water to form a water phase, adding an oil phase, a surfactant and a cosurfactant, and fully stirring to form a microemulsion, wherein the oil phase is alkane or cycloalkane, the surfactant is an ionic surfactant and/or a nonionic surfactant, and the cosurfactant is organic alcohol.

6. The alkyne selective hydrogenation catalyst of claim 5 wherein the oil phase is a C6 to C8 saturated alkane or cycloalkane, preferably cyclohexane, n-hexane; the surfactant is an ionic surfactant and/or a nonionic surfactant, preferably a nonionic surfactant, more preferably polyethylene glycol octyl phenyl ether or cetyl trimethyl ammonium bromide; the cosurfactant is a C4-C6 alcohol, preferably n-butanol and/or n-pentanol.

7. The alkyne selective hydrogenation catalyst of claim 5 or 6, wherein the microemulsion has a weight ratio of water phase to oil phase of 4.8 to 6.8, a weight ratio of surfactant to oil phase of 0.08 to 0.30, and a weight ratio of surfactant to cosurfactant of 1.0 to 1.2.

8. The alkyne selective hydrogenation catalyst of claim 1 wherein during the catalyst preparation, the step of loading the microemulsion with Pd follows the step of loading the microemulsion with Ni and Cu.

9. The alkyne selective hydrogenation catalyst of claim 1, wherein the catalyst is carried out in a solution process of Pd and the loading sequence of Ni/Cu is not limited in the preparation process; the sequence of the step of loading Pd by the solution method and the step of loading Fe and Zn by the solution method is not limited.

10. The alkyne selective hydrogenation catalyst according to claim 1, wherein the preparation process comprises the following steps:

(1) Dissolving precursor salts of Ni and Cu in water, adding an oil phase, a surfactant and a cosurfactant, fully stirring to form a microemulsion, controlling the particle size of the microemulsion to be more than 80nm and less than 950nm, adding a carrier into the prepared microemulsion, soaking for 0.5-4 hours, filtering out residual liquid, drying at 60-120 ℃ for 1-6 hours, and roasting at 300-600 ℃ for 2-8 hours to obtain a semi-finished catalyst A;

(3) The loading of Fe and Zn is carried out by a supersaturation impregnation method, the prepared mixed solution of ferric salt and zinc salt is 80-110% of the saturated water absorption rate of the carrier, the pH value is adjusted to 1-5, and the semi-finished catalyst B is roasted between 500-550 ℃ after being loaded with Fe and Zn for 4-6 hours to obtain a semi-finished catalyst C;

(4) Dissolving Pd precursor salt in water, adding an oil phase, a surfactant and a cosurfactant, fully stirring to form microemulsion, controlling the particle size of the microemulsion to be more than 80nm and less than 950nm, adding a semi-finished catalyst C into the prepared microemulsion, soaking for 0.5-4 hours, filtering out residual liquid, drying at 60-120 ℃ for 1-6 hours, and roasting at 300-600 ℃ for 2-8 hours to obtain the required catalyst.